Low Sun Exposure Is Associated with Both Progressive-Onset and Relapse-Onset Multiple Sclerosis Risk: A Case-Control...

Area of Science:

• Epidemiology
• Environmental Health
• Neurology

Background:

• Sun exposure is linked to multiple sclerosis (MS) onset, but studies often lack differentiation between progressive-onset MS (POMS) and relapse-onset MS (ROMS).
• Previous research has not consistently reported risk estimates separately for POMS and ROMS regarding sun exposure.

Purpose of the Study:

• To investigate the association between pre-disease sun exposure and the risk of POMS.
• To compare the effect of sun exposure on POMS versus ROMS.

Main Methods:

• A nationwide case-control study utilizing data from the PPMS and Ausimmune studies.
• Inclusion of 153 POMS cases, 204 ROMS cases, and 558 controls.
• Assessment of sun exposure via self-reported time, satellite-derived UVR dose, and adjustment for covariates using logistic regression.

Main Results:

• Higher cumulative ultraviolet radiation (UVR) exposure demonstrated a dose-response association with reduced risk for both POMS and ROMS.
• The association between UVR exposure and reduced MS risk was consistently stronger for POMS than for ROMS.
• Leisure-time UVR dose (per 100 kJ/m2 increment) showed a significant association with POMS (aOR 0.93) and ROMS (aOR 0.96), with a significant interaction effect (p < 0.001).

Conclusions:

• Lifelong low sun exposure is associated with an increased risk of both POMS and ROMS.
• The protective effect of sun exposure against MS onset is more pronounced in POMS compared to ROMS.